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#11654 - 05/31/06 1:29 pm Boyer Bransden, kickback at start BSA Spitfire,  
Joined: May 2006
Posts: 198
oleandreas Offline
BritBike Forum member
oleandreas  Offline
BritBike Forum member

Joined: May 2006
Posts: 198
Tynset Norway
Hello

I have a BSA A 65, 1968 mod. 650 ccm. 9:1 in compression, new AMAL 32 mm consentrics, sound engine. coils is fine. electrics and battery exellent, 13.5 volt. I have a correct mark on the crank at 34 degree BTDC and use strobo lamp

I have a older Boyer Bransden mk III and have problems with KICKBACK at start When THE gnition is correctly set at 34 degrees BTDC - 5000 rev min. When I adjust ignition to ignite earlier,(retard i guess?) it does not kick back so hard and much and it runs much smoother on low revs and tickover, but I can clearly feel that the engine dont run free on high revs (5000 o min).

I wonder what to do, seems like the advancecurve is not right ?? to short or ?

Will it help to buy a newer Boyer ignition module ?
Is there possible to adjust the Boyer Bransden Micro Digital ignition curve, and in case how is the adjustment of curve done ?
Or is it better to buy the Boyer B Micro Power ?

Anybody have i suggestion ?

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#11655 - 05/31/06 3:20 pm Re: Boyer Bransden, kickback at start BSA Spitfire,  
Joined: Feb 2005
Posts: 622
Tom Sanders Offline
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Tom Sanders  Offline
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Joined: Feb 2005
Posts: 622
Winter Springs, FL
Don'y worry about it. Run it.

I had the same problem on a 72 commando using a Boyer. My mechanical mentor, Windy, and I set the timing with a strobe but I still got kick back upon starting. I retarded the timing a little bit. No more kick back and the motor runs great.


LONG LIVE LOCKTITE

74 Roadster 880cc
1962 Norton 650SS
75 Ducati 860GT
1968 Commando Fastback SN 126157
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#11656 - 05/31/06 5:52 pm Re: Boyer Bransden, kickback at start BSA Spitfire,  
Joined: Aug 2001
Posts: 6,857
triton thrasher Online content
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triton thrasher  Online Content
BritBike Forum member

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Posts: 6,857
scotland
This looks like a useful guide:

link


Amateur Loctite enthusiast.
#11657 - 06/01/06 1:09 am Re: Boyer Bransden, kickback at start BSA Spitfire,  
Joined: Aug 2001
Posts: 3,348
BONZO R.I.P. Offline
In Remembrance
BONZO R.I.P.  Offline
In Remembrance

Joined: Aug 2001
Posts: 3,348
Michigan, USA
You might try switching the leads from the stator plate(the thing that replaces the points plate ) to the black box , I've heard this can cause the advance to shut off , and I have evn heard it can retard as the revs increase if the wires are crossed ???

FWIW-BONZO

#11658 - 06/01/06 7:16 am Re: Boyer Bransden, kickback at start BSA Spitfire,  
Joined: May 2006
Posts: 198
oleandreas Offline
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oleandreas  Offline
BritBike Forum member

Joined: May 2006
Posts: 198
Tynset Norway
Thank you guys for help, the wires is not interchanged from the pick up.

My main question is if the old Boyer Bransden mkIII has a different or shorter ignitoncurve than the newer Boyer ignitions like micro power and micro didgital.

#11659 - 06/01/06 11:02 am Re: Boyer Bransden, kickback at start BSA Spitfire,  
Joined: Dec 2004
Posts: 8,877
kommando Online content
kommando  Online Content


Joined: Dec 2004
Posts: 8,877
Scotland
Yes they do have different curves go to Dyno Daves site for more info.

http://atlanticgreen.com/

#11660 - 06/01/06 12:37 pm Re: Boyer Bransden, kickback at start BSA Spitfire,  
Joined: Mar 2005
Posts: 9,962
John Healy Online content
John Healy  Online Content


Joined: Mar 2005
Posts: 9,962
Boston, Massachusetts
Quote:
Originally posted by oleandreas:
Hello

I have a BSA A 65, 1968 mod. 650 ccm. 9:1 in compression, new AMAL 32 mm consentrics, sound engine. coils is fine. electrics and battery exellent, 13.5 volt. I have a correct mark on the crank at 34 degree BTDC and use strobo lamp

I have a older Boyer Bransden mk III and have problems with KICKBACK at start When THE gnition is correctly set at 34 degrees BTDC - 5000 rev min. When I adjust ignition to ignite earlier,(retard i guess?) it does not kick back so hard and much and it runs much smoother on low revs and tickover, but I can clearly feel that the engine dont run free on high revs (5000 o min).

I wonder what to do, seems like the advancecurve is not right ?? to short or ?

Will it help to buy a newer Boyer ignition module ?
Is there possible to adjust the Boyer Bransden Micro Digital ignition curve, and in case how is the adjustment of curve done ?
Or is it better to buy the Boyer B Micro Power ?

Anybody have i suggestion ?
First, the unit can be tested by Boyer, and if it is less than 5 years after the production date printed on the label, be replaced under Boyer's warranty. If it is not still under warranty, and the unit has failed, they can organize a replacement unit for you. As you have a trigger unit, to upgrade all you would have to do is by a new box: MKIII, Micro-Digital or Micro-Power (new coils would be required).

As far as the ignition advance curve for the Micro-Power and Micro-Digital it is pre-programmed during production and cannot be re-programmed. Boyer offers a service, for a nominal charge, where they will program ANY advance curve you desire (only Micro-Digital and Micro-Power units).

The typical Micro-Digital advance curve reflects that a motor starts better with a bit more advance than is required for idling. So with tha ability to program the computer "chip" Boyer actually programs it so that it has some initial advance only to retard after starting for a stable idle. With the Micro units for a nominal charge you can request any advance curve your heart desires.

People are confused about swapping the black/yellow and black/white wires. If you cross the wires the box will change the time it fires the coil by approximately 30 degrees (60 crank degrees). With the wires crossed the bike will not start until it is retimed.

It is true, that when you cross the wires, you basically have a fixed advance ignition. There will be little, if any, change where the ignition fires the plug as the rpm's increase when the wires are crossed. It also means that you have to use the opposite timing hole (in your case instead of using the counter-clockwise rotation timing hole you would have to use the clock-wise hole).

The fact that you have 13.5 volts at the battery (?) is interesting, but is not a true test of the voltage available to the box. Resistances to the flow of electricity going to the box and resistances coming from the box through the ground circuit could dramtically reduce the available voltage at the box.

There is one problem when trying to measure voltage (volt-drop) in the Boyer's power circuit: the switching diode is normally turned off or open. To use a bulb or volt meter to check for voltage drops requires closing the circuit. This is done by by-passing the Boyer box by moving the wire that feeds the box directly to the coil. On a positive ground system this means you take the wire that is connected to the boxes' white wire and move it to the coil post you have connected the boxes' black wire.

Having completed the circuit you can now use your bulb or volt meter to check for voltage drops either side of the coil. You should have full battery voltage at the feed side of the coil and no voltage at the ground side. If the bulb does not glow FULLY on the feed side or there is any glow at all on the ground side you have a problem with the battery, feed or ground circuit.

An "open circuit" voltage measurement of the battery is a meaningless exercise. You need to test the battery with one of the new impedance or load test units to verify its condition. A more meaningfull test, although not perfect, can be performed by running the headlight and brake light for a period of time and while watching the voltage at the battery.

The 13.5 volts would only be present if the battery was just taken off a battery charger as there is a little "bounce" to the voltage for a few minutes after it is removed from the charger. You should be seeing over 14 volts if the bike is running and approx. 12.8 if the bike is sitting. You don't need a new battery, but a good battery. If it has gone high resistance or there is a mechanical break inside the battery it will never be a good battery, even if it can be charged and you have an open circuit voltage of 12.8 volts. Once you apply a load to a high resistance battery or one with a mechanical break the voltage will fall below aceptable levels.
2c
john



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